linux-kernel - Re: [PATCH] arm64/vmcore: Add pgtable_l5

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Message-ID: <Zs5Xo5eVUvGMbtSv@MiWiFi-R3L-srv>
Date: Wed, 28 Aug 2024 06:48:03 +0800
From: Baoquan He <bhe@...hat.com>
To: Will Deacon <will@...nel.org>
Cc: k-hagio-ab@....com, lijiang@...hat.com,
	Kuan-Ying Lee <kuan-ying.lee@...onical.com>,
	Vivek Goyal <vgoyal@...hat.com>, Dave Young <dyoung@...hat.com>,
	Jonathan Corbet <corbet@....net>,
	Catalin Marinas <catalin.marinas@....com>,
	kexec@...ts.infradead.org, linux-doc@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	ardb@...nel.org
Subject: Re: [PATCH] arm64/vmcore: Add pgtable_l5_enabled information in
 vmcoreinfo

On 08/27/24 at 01:24pm, Will Deacon wrote:
> On Mon, Aug 26, 2024 at 02:52:02PM +0800, Kuan-Ying Lee wrote:
> > Since arm64 supports 5-level page tables, we need to add this
> > information to vmcoreinfo to make debug tools know if 5-level
> > page table is enabled or not.
> > 
> > Missing this information will break the debug tool like crash [1].
> > 
> > [1] https://github.com/crash-utility/crash
> > 
> > Signed-off-by: Kuan-Ying Lee <kuan-ying.lee@...onical.com>
> > ---
> >  Documentation/admin-guide/kdump/vmcoreinfo.rst | 6 ++++++
> >  arch/arm64/kernel/vmcore_info.c                | 3 +++
> >  2 files changed, 9 insertions(+)
> 
> In which case, wouldn't you also want to know about pgtable_l4_enabled()?

That is a good question. I guess it's deduced in code, mostly needed for
different PAGE_OFFSET, how to transfer virtual addr to physical addr,
etc.

Add Crash utility experts here.